1. Field of the Invention
The present invention relates to a robot controller having detachable teaching pendant.
2. Description of the Related Art
While teaching operation of a robot, a teaching pendant connected to a controller of the robot may be used. In general, the teaching pendant is used for teaching or retrieval operation of the robot, and thus is not used during automatic operation of the robot. However, in the conventional robot, since one teaching pendant is connected to one controller, the cost of a system including a plurality of robots tends increase.
On the other hand, it is a well-known technique to use a teaching pendant which is detachable from a robot controller. In this case, it is necessary to suspend the operation of the robot when the teaching pendant is attached to or detached from the controller. For example, JP H05-042493 A discloses a teaching pendant including an emergency stop circuit having a connection/disconnection switch, and a prohibiting means for prohibiting the operation of an emergency stop means when the teaching pendant is disconnected from a robot controller during the switch is pushed (or in the “ON” state).
In JP H05-042493 A, the automatic operation of the robot can be continued even when the teaching pendant is detached from the robot controller, and the emergency stop of the robot can be avoided when the robot should not be brought to an emergency stop. However, even when the connection/disconnection switch is pushed (or in the “ON” state), in some cases, the robot should be brought to the emergency stop (or a drive power for the robot should be shutoff), from the standpoint of safety of an operator. JP H05-042493 A does not disclose a practical means for appropriately dealing with such a case.